Removal and fouling mechanisms in nanofiltration of polysaccharide solutions

Tubular membrane filtration is an important process when feed waters with a relatively high solids content are filtered. Such solids would normally have to be removed in a pre-treatment stage if spiral wound modules are to be used. High solids content occurs for example in high turbidity surface waters, wastewaters that contain fibrous materials or in waters where coagulants are added. Tubular membranes can be used directly in nanofiltration (NF) and in this study fouling by a solution containing polysaccharides is examined. The study was designed in view of a wastewater recycling application where polysaccharides like cellulose are a major constituent of the effluent organic matter (EfOM) and colloidal organics. The investigation was performed with various organic compounds and varying solution chemistry namely pH and ionic strength. Two solutes in several concentrations have been used: Cellulose (particulate) and microcrystalline cellulose (colloidal) in addition with various CaCl2 and NaCl concentrations. The operating parameters investigated were cross flow velocity, transmembrane pressure (TMP) and pH. Membranes were cleaned after each filtration experiment and flux recovery was measured. As a general trend, it was observed that with increasing cellulose concentration fouling increases and that solution chemistry plays an important role in the association of foulants with the membranes. The permeability decreases for high and neutral pH conditions in the presence of salt ions. Calcium affects the flux more than sodium. The permeability at acidic pH values is relatively low and not influenced by the ions as much as for other pH conditions. Electrostatic interactions between membrane, salt ions and cellulose can explain this behaviour. Calcium ions were confirmed to play an important role in membrane fouling. Increasing cross flow velocity decreases the reversible fouling but increases the irreversible fouling

Electronic Medical Records: Provotype visualisation maximises clinical usability

The Electronic Medical Record (EMR) is the essential tool of the clinical consultation, effectively replacing the paper medical record. Since its gradual adoption in the early 2000s there has been a failure to achieve even moderate levels of EMR usability in clinical settings, resulting in a negative impact on clinical care, time efficiency and patient safety. This research explores how deeper collaboration with clinical users through participatory design, drawing on the disciplines of visual design, user experience (UX) design and visual analytics, might offer a more effective approach to this important problem. The lead researcher for this project is both a practising doctor and design researcher. Usability of two commercial EMR interfaces in the field of sexual health is explored through a mixed method survey, with responses used to inform the design of an interface provotype. This in turn is evaluated through repeat survey and ‘test-drive’ talk-aloud workshops. Results from the survey on two commercial EMR interfaces (n=49) revealed deep dissatisfaction particularly around issues of navigation, flow of consultation, frustration, safety, time-dependent and time-independent data, data complexity and data salience. Comparative provotype evaluation (n=63) showed that clinically-relevant visualisation offers marked gains in clinical usability and performance. This research argues for a re-imagining of the way we look at medical data during the clinical consultation so that the affordances and benefits of the digital format can be exploited more fully. It highlights the value of combining participatory design with visualisation to embed explicit, experiential and even tacit clinical knowledge into the EMR interface

A visual economy of individuals The use of portrait photography in the nineteenth-century human sciences

SIGLEAvailable from British Library Document Supply Centre-DSC:DX210225 / BLDSC - British Library Document Supply CentreGBUnited Kingdo